A New York City passenger train derailed in the Bronx early Sunday morning, leaving at least four people dead and more than 60 injured.

Gov. Andrew Cuomo confirmed the casualties, speaking from the scene hours after the accident. He said authorities believed they have everyone accounted for, and that representatives from the National Transportation Safety Board are en route.

At least 67 passengers were injured, The New York Timesreports, 11 critically, when a train from Poughkeepsie, NY, derailed under the Henry Hudson Bridge at about 7:20 a.m. in the Bronx, according to Metropolitan Transportation Authority spokesman Aaron Donovan. Four or five cars of the seven-car train left the tracks about 100 yards north of the station, but none entered the adjacent Hudson and Harlem rivers, the MTA said.

Three of the four people who were killed were thrown from the train during the derailment, FDNY Chief of Department Ed Kilduff said. Among the victims were a 14-year-old boy and his father as well as a 21-year-old woman with a broken leg and a 43-year-old man with a spinal cord injury, NBC News reports. The train operator was also injured but is conscious, Police Commissioner Ray Kelly said.

It was not immediately clear what caused the accident, but MTA spokeswoman Marjorie Anders said the curve on the track where the derailment occurred is a slow-speed area. The black box should be able to tell investigators how fast the train was traveling. Officials will also examine the track, equipment, signal system and operator. Overturned cars will be righted to check for additional victims.

The National Transportation Safety Board will lead an investigation into the causes of the accident, after which time the MTA will be able to repair the tracks and train. A crane is currently en route to the accident, but Gov. Cuomo advised at a press conference Sunday evening that commuters should plan for a long commute Monday or use the Harlem line.

A White House spokesperson said that President Obama was briefed by Lisa Monaco, assistant to the President for Homeland Security and Counterterrorism, shortly after the incident occurred. “His thoughts and prayers go out to the friends and families who lost a loved one and everyone affected by this incident,” a White House statement read.

Metro North services between the Croton-Harmon station and Grand Central Terminal are currently suspended, Donovan said. Amtrak service between New York City and Albany resumed in the afternoon, after having been suspended after the crash.

Authorities are asking those who are looking for family members who may have been on the train to call 718-817-7444 or go to the John F. Kennedy High School at 99 Terrace View Ave. in the Bronx, which has been designated as the family center.